Venomous jelly fish have a significant economic and health impact on man and can induce a number of physiological activities of biomedical interest. The sea nettle, a venomous jellyfish found in abundance in the Chesapeake Bay, can inflict pain in man and the venom produces a lethal cardiac effect in mice. This cardiotoxin is similar in action to that of the sea wasp and man-o'war and may serve as a model for the investigation of those venoms. The neurotoxin, kinin-like factors, dermonecrotic factor and certain enzymes such as proteases and endonucleases may contribute to the production of pain. Efforts will be made to further isolate and chemically characterize these factors of the venom. Some properties of the venoms such as its similarity to lectins and the fact that it contains an endonuclease may contribute to our understanding of cellular attraction and behavior as well as nucleic acid repair and carcinogenesis. Study of the immunological aspects of nettle envenomation will be continued as nettle specific IgE and IgG antibodies will be assayed in controls and in patients who have had exaggerated reactions to stinging in order to define the role of these antibodies in the pathogenesis of the sting. A higher degree of purification of the venom's pain producing and lethal factors will be attempted by the use of stabilizers, techniques to increase the yield of present purification schemes, affinity chromatography and isoelectric focusing. Development of a more rapid assay system for toxicological actions involves the use of purified, monoclonal antibody, cell culture techniques and erythrocyte agglutination tests. The action of the neurotoxin against cutaneous sensory nerves will be studied and the effect of the cardiotoxin on calcium membrane transport within the heart will be investigated. The mouse writhing test will be employed as an indicator of pain. The effect of any isolated factors such as the kinin-like principle or the endonuclease will be investigated and compared with those found in other coelenterate venoms.